System for voice control of a medical implant

ABSTRACT

A system for communicating with a medical implant in a body of a user is provided. The system comprises a command generator and a memory, wherein the command generator is configured to receive a voice command from the user and to reduce noise, generated by the body, from the received voice command to generate a noise-reduced voice command. The command generator is further configured to compare the noise-reduced voice command with previously stored voice commands and to transmit a command signal to the implant in case the noise-reduced voice command corresponds to any of the previously received commands stored in the memory.

TECHNICAL FIELD

The present invention discloses a system for voice control of andcommunication with a medical implant for implantation in a mammal body.

BACKGROUND

Medical implants as such are previously known, and are often used toreplace or assist an organ or a function in a mammal body. Some medicalimplants which may be mentioned by way of example are artificial hipjoints, pacemakers, artificial insulin pumps and the like.

As will be understood, some medical implants require, or may be improvedby, the ability to receive input, either from the patient or medicalpersonnel attending to the patient. Various methods are known for givingsuch input to implanted devices. For example, U.S. Pat. No. 5,569,186,discloses a system for sending input to an implant via telemetry. In the'186 patent, input can be given as voice commands; if a voice command issuccessfully recognized by the apparatus, a matching command is thensent by telemetry means to an implantable device in a patient's body.

SUMMARY

It is an object of the present invention to further improve on theability of a medical implant to receive input commands as voicecommands.

This object is addressed by the present invention in that it discloses asystem for implantation in a mammal body for the control of andcommunication with a medical implant in the mammal body; the system ofthe invention comprises a command input device and a processing devicecoupled to the command input device.

The processing device of the system is adapted to generate input to acommand generator which is also comprised in the system and which iscoupled to the processing device and adapted to generate and communicatecommands to the medical implant in response to input received from theprocessing device.

Furthermore, the system of the invention also comprises a memory unitconnected to at least one of said devices in the system for storing amemory bank of commands.

The inventive system exhibits the following features:

-   -   it is adapted to be implanted in proximity to the medical        implant,    -   the command input device is adapted to receive commands from a        user as voice commands,    -   the commands stored in the memory unit include voice commands,    -   the processing device comprises a filter for filtering input        received via the command input device,    -   the filter is adapted to filter received voice commands against        the background of high frequency losses and frequency distortion        caused by the mammal body,    -   the processing device is adapted to deliver filtered voice        commands as input to the command generator which is adapted to        compare received voice commands to voice commands stored in the        memory unit, and if that comparison yields a likeness, to        generate a corresponding command and communicate it to the        medical implant.

Thus, by means of the invention, a user can control an implant in amammal body by means of voice commands, i.e. spoken commands, whichnaturally will enhance the ease of handing for the user.

The inventor of the present invention has realized that a mammal bodysuch as the human body causes losses, in particular high frequencylosses and c frequency distortion to acoustic signals such as voicecommands which are generated outside of the body. Both of these factorsare taken into account by the filter of the present invention, i.e. thelosses and the distortion to outside sounds caused by the body, as hasemerged from the description given above.

In one embodiment the filter is adapted to filter received voicecommands against the background of high frequency losses and frequencydistortion caused by the mammal body based on the specific position ofsaid command input device inside the body.

The filter may have different frequency compensation curves tocompensate for the resulting voice command after passing through themammal body based on the specific position of said command input deviceinside the body.

The filter may also have different time delay compensations tocompensate for the resulting voice command after passing through themammal body based on the specific position of said command input deviceinside the body.

In addition, noises caused by the body as such may also interfere withthe command input device's reception of voice commands, so in oneembodiment of the present invention, the processing device is alsoadapted to cancel noise which is caused by the mammal body and receivedby the command input device, in order to reduce or entirely eliminatethe amount of such noise comprised in the input to the commandgenerator.

In one embodiment of the inventive system, the processing device isadapted to recognize one more specific noise sources in the mammal body,and to activate the cancellation when noise from such a noise source isdetected.

In one embodiment, the cancellation is only activated when theprocessing device receives a voice input command from a user.

In particular, the internal “noise sources” which the system is adaptedto cancel noise from comprise one or more of the following:

-   -   the intestines,    -   the respiratory system,    -   the heart.

As an alternative to direct cancellation, the processing device takesinto account the specific internal sounds such as, for example,heartbeats or respiratory sounds in order to be able to process voicecommands. The noise cancellation in such an embodiment means an activeprocessing to counteract the effect of such internally generated sounds.

The voice commands which are stored in the memory of the system of theinvention can either be preset by a manufacturer, as an alternative towhich they can be “learned” by the system prior to implantation. In thelatter case, the commands can be learned on a separate learning device,and then stored in the system's memory. As an alternative to a separatelearning device, in one embodiment of the invention, the commandgenerator comprises a learning function which is adapted to performlearning sessions for learning which of a number of voice commands thatshould be interpreted as meaning one of a number of pre-programmedcommands stored in the memory.

In other words, a user utters a certain command a number of times untilthe system recognizes the command, and the recognized command is thenassociated with a control command which should be output to the implantwhen the recognized command is received by the system.

In one embodiment, the system of the invention additionally comprises awireless receiver for receiving commands from a remote control outsideof the mammal body. The commands comprise commands which should also begenerated by the command generator upon recognizing a voice command froma user, so that a voice command issued by a user can be accompanied by awireless command from the remote control during a learning session, inorder for the learning function to learn which command that should begenerated upon the reception of a certain voice command.

In one embodiment, the system also comprises a wireless transmitter,which the learning function is adapted to use in order to signal to auser during a learning session that a voice command has been learnt bythe learning function.

As has been mentioned, the system of the invention is intended forimplantation in a mammal body, and is in one embodiment particularlysuitable for implantation in the abdomen, thorax or the pelvic region ofthe mammal body, since, for example, different sound spectra generatedby the body and different sound distortion and frequency losses generatespecific patterns for each of these locations.

In one embodiment, the command generator and/or the processing devicecomprises means for receiving signals from the medical implant and fortransmitting said signals to a user. In one version of this embodiment,the system uses the transmitter of the learning function fortransmitting the received signals from the medical implant wirelessly tothe user. The transmitter can be a radio transmitter or a sonictransmitter.

The implant which is controlled by means of the present invention can beof various kinds, all of which are within the scope of the presentinvention, but examples of which mention may be made include thefollowing:

-   -   A controllable engine,    -   A pump,    -   A stimulation device,    -   A constriction device,    -   A fluid moving device,    -   A heart pump,    -   A heart valve,    -   A filtering device,    -   A pharmaceutical drug delivery device,    -   An artificial reservoir,    -   A fertility or non-fertility device,    -   A no-reflux device,    -   A potency treatment device,    -   A urine incontinence or urine retention device,    -   An intestinal device,    -   An aneurysm treatment device,    -   A hypertension treatment device,    -   A clot removing device

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail in the following, withreference to the appended drawings, in which

FIG. 1 shows an overview of one embodiment of a system of the invention,and

FIG. 2 shows a measured transfer function curve, and

FIGS. 3-5 show measured noise curves, and

FIG. 6 shows a block diagram of some components of one embodiment of thesystem of the invention, and

FIG. 7 shows an overview of one embodiment of a system of the invention,and

FIG. 8 shows a block diagram of some components of one embodiment of thesystem of the invention, and

FIGS. 9 and 10 illustrate a filter used in some embodiments of theinvention, and

FIG. 11 shows a block diagram of an alternative design of the invention,and

FIG. 12 shows a state diagram, and

FIG. 13 shows a block diagram of a possible component used in theinvention, and

FIGS. 14-26 show various embodiments of solutions for powering thesystem of the invention.

DETAILED DESCRIPTION

FIG. 1 shows an overview of a system 11 of the invention. The system 11is shown as being implanted in a mammal body, in this case a human body10, and as can be seen, the system 11 is electrically connected to amedical implant 17 in the body 10.

The system 10 is intended to control the medical implant 17, and isadapted to be implanted so close to the medical implant 17 that theelectrical connection, shows as 18 in FIG. 1, can be a wire-boundconnection, although wireless connections are also fully within thescope of the present invention.

The system 11 and its components will be described in more detail in thefollowing, but first an overview of the system's components in theembodiment shown in FIG. 1 will be given. The function of the componentsof the system 11 will also be explained in more detail following theoverview.

The system 11 comprises a command input device 12; since the system 11is intended to be able to receive commands in the form of spokencommands, the command input device suitably one or more microphones; inthe case of more than one microphone, the microphones can be arranged asa so called microphone array. The system 11 also comprises a processingdevice 13, for example in the form of a microprocessor, and connectedto, or incorporated in the processing device 13 there is a filter 14. Itshould be pointed out that the placement of the filter 14 can be variedwithin the scope of the invention; for example, the filter 14 can alsobe placed immediately following the command input device 12, i.e.between the command input device and the processing device 13. Asmentioned, the filter 14 can either be comprised in the processingdevice 13 as such, or it can be separate system component in the system11.

In addition, the system 11 as such can be an analogue system, i.e. onewhich uses analogue signals and analogue components, or, alternatively,in a preferred embodiment, the system is based on digital components,and therefore comprises an analogue to digital converter, an ADC, whichcan be placed for example, immediately following the command inputdevice 12. The ADC can also be a sub-function in the processing device13. The fact that the system 11 of the invention can be either analogueor digital is true for all of the embodiments described below; the samegoes for the reasoning regarding the placement of the ADC.

The system 11 also comprises a command generator 16 and a memory 15,with the memory being coupled to the command generator 16 and/or to theprocessing device 16.

One function of the command generator 16 is to receive voice commandswhich have been received from a user via the command input device 12,filtered by the filter 14 and possibly also processed by the processor13, and to then compare these voice commands with a set of “allowed”voice commands stored in the memory 15; if the comparison yields apositive result, i.e. a received command matches one of the storedcommands, the command generator will then output a corresponding commandon the connection 18 to the implant 17 for controlling the implant 17.

The notion of “corresponding command” which is output to the implant 17is needed if the implant can only receive commands as non-spokencommands. Naturally, if the implant 17 as such can accept spokencommands, the system 11 can be adapted so that the command generator 16can output the commands to the implant 17 as spoken commands.

In one embodiment, the command generator 16 has an output stage whichcomprises a conductor connected to the medical implant in order totransport commands to the implantable device in response to inputreceived from the processing device 13.

More details on how the system 11 of the invention is adapted to receivespoken commands will be given later in this text. However, first, thefunction of the filter 14 will be described in more detail.

Since the system 11 of the invention, including the command input device12, is intended to be implanted inside a mammal body, the inventor ofthe present invention has realized that the mammal body will have atransfer function on audio signals, e.g. voice commands, which aregenerated outside the body before they reach the command input device12. This transfer function needs to be counteracted in order to ensuregood function of the system 11. To this end, measurements have been madeinside a mammal body, in this case a human body, in order to find thetransfer function of the human body.

FIG. 2 shows a typical transfer function for sound generated outside ofa human body as detected by a microphone inside the abdomen. As can beseen, the transfer function exhibits a strong “roll off” in thefrequency range above 1 kHz, and an amplification of the frequency rangebelow 100 Hz.

Thus, the filter 14 should be such that it can counteract the transferfunction of FIG. 2. Naturally though, the transfer function shown inFIG. 2 and the position in the body where it was measured, i.e. theabdomen, are only examples, as is the human body; the same principlesare applicable to other mammal bodies as well. In other embodiments ofthe invention, the transfer function of more than one position in thebody can be measured, and the filter 14 can be programmed or otherwisedesigned to counteract a transfer function which is specific for aposition in the body for which the system 11 is intended, or the filter14 can be programmed with a number of filter characteristics, one ofwhich can be activated, depending on which position in the body that thesystem 11 is intended to placed in.

As a further alternative, the filter 14 and/or the processing device 13can be programmed to detect which of a number of pre-programmed filterfunctions that best fit the actual transfer function in the positionthat the system 11 is placed in, so that that system 11 can be“adaptive” in that it chooses one of a number of pre-programmed filterfunctions that is best suited to the placement of the system 11 afterthe system is actually implanted in the mammal body 10.

The filter 14 can, as has been mentioned, and as will be realized bythose skilled in the field, be designed in a variety of ways, but in oneembodiment, the filter 14 is implemented as a digital filter usingalgorithms for digital signal processing.

In one embodiment the filter 14 is adapted to filter received voicecommands against the background of high frequency losses and frequencydistortion caused by the mammal body 10 based on the specific positionof said command input device 12 inside the body.

The filter 14 may have different frequency compensation curves tocompensate for the resulting voice command after passing through themammal body 10 based on the specific position of said command inputdevice 12 inside the body.

The filter 14 may also have different time delay compensations tocompensate for the resulting voice command after passing through themammal body 10 based on the specific position of said command inputdevice 12 inside the body.

Since the system 11 is adapted to be implanted inside a mammal body, thecommand input device and conceivably also other parts of the system, maybe enclosed in a watertight casing, which will also cause somedistortion and loss on audio signals. To compensate for this, in oneembodiment, the filter 14 is also adapted to compensate for losses anddistortions caused by such a casing.

Apart from the effects of the mammal body on the voice commandsgenerated outside of the mammal body as the commands propagate throughthe body 10 to the input device 12, in some embodiments of the system10, the system is also adapted to counteract noises generated within thebody, by the body itself, sounds which may interfere with the functionof the input device 12 if they are not addressed properly. To this end,the inventor of the present invention has made measurements inside ahuman body (as an example of a mammal body), in order to ascertain ifthere are indeed such noises generated inside a mammal body and whattheir exact nature is, in order to see how they may be bestcounteracted.

Although noises inside of a mammal body such as the human body may becaused by a large number of organs, some main sources of internal noisehave been found to be:

-   -   the intestines,    -   the respiratory system,    -   the heart's beating.

The inventor of the present invention has performed measurements insidea human body, as an example of a mammal body, in order to ascertain thenature of these noises, in order to determine how best to counteractthese noises.

FIGS. 3, 4 and 5 show typical noise generated inside a human body by theintestines, FIG. 3, the respiratory system, FIG. 4, and the heart'sbeating, FIG. 5.

Suitably, the system 11 comprises a function for cancelling such noises,preferably located in the processing unit 12. The cancellation functionis preferably also implemented as a DSP algorithm, and serves to reduceor entirely eliminate the amount of such noise in the input to thecommand generator.

This is shown schematically in a block diagram in FIG. 6, which shows adynamic noise cancellation function 19 attached to the processor 13.Naturally, the cancellation function 17 can either be an integrated partof the processor 16, or it can be a separate component which isconnected to the processor 13. The block diagram of FIG. 6 also shows ablock for a learning function for learning voice commands, about whichmore will be said later in this text.

The cancellation function 19 can be activated in a number of ways, invarious embodiments of the invention:

In one embodiment, the cancellation function 19 is constantly active,whilst in another embodiment, the cancellation function 19 is adapted torecognize one or more specific noise sources in the mammal body 10, andto activate said cancellation when noise from such a noise source isdetected. Thus, in the latter embodiment, the cancellation function 19can be said to be “sleeping” when there is an absence of internallygenerated noise in the body 10. The term “absence” should here be takento mean that such noises are below a predefined threshold, above whichthe cancellation is activated and carries out its cancelling function.

In a further embodiment, the system 11 comprises a function forrecognizing when a user issues spoken commands, and then activates thecancellation function.

Returning now to the issue of the voice recognition function of thesystem 11, the system 11 will, as mentioned, in one embodiment comprise,suitably in the command generator 16, a learning function which isadapted to perform learning sessions for learning which of a number ofvoice commands that should be interpreted as meaning one of a number ofpre-programmed commands stored in the memory 15.

The learning sessions can be performed before the system 11 is implantedin the patient, in which case the system 11 will be exposed to a numberof voice commands, until the learning function has learnt to recognizethese commands, at which point in time recognized commands can beassociated with a certain command that should be output to the medicalimplant 17. For example, if one of the commands that have beenrecognized is “open”, an operator will then indicate to the system 11 bymeans of an interface that the command “open” should result in a certainelectrical signal or command being output on the connection 18 to theimplant 17.

The learning and recognition can either be such that the learningfunction learns to recognize commands only from a certain set ofindividuals who are authorized to operate the medical implant 17, or thelearning and recognition can be such that the earning function learns aset of commands to recognize regardless of the identity of the speaker.

Alternatively, or as a complement, the leaning function can also in oneembodiment be adapted for learning in situ. In such a case, the system11 will comprise a wireless receiver for receiving commands from aremote control outside of the mammal body, which commands will comprisecommands which should also be generated by the command generator uponrecognizing a voice command from a user, so that a voice command issuedby a user can be accompanied by a wireless command from the remotecontrol during a learning session, in order for the learning function tolearn which command that should be generated upon the reception of acertain voice command.

Using the example of the word “open” again, a user will then set thesystem in its learning mode, and utter the word “open” a number oftimes, following which the user will use the remote control to activatethe command which should be triggered by the word “open”, thusassociating that command with the word “open”.

As shown in FIG. 7, as a complement to this procedure, a version 11′ ofthe system can also comprise a wireless transmitter 71, which thelearning function is adapted to use in order to signal to a user duringa learning session that a voice command has been learnt by the learningfunction. Thus, the user can be alerted to the fact that the learningfunction has learnt the word “open”, upon which the user uses a remotecontrol to activate the command which should be associated with thatword, and then terminates the learning function, or goes on to teach thelearning function another word or phrase.

In those embodiments 11′ where the system comprises the wirelesstransmitter 71 for communicating with a user, such a transmitter 71 canalso be used in the following manner: the command generator 16 and/orthe processing device 13 comprises means for receiving signals from themedical implant, and the system then uses the transmitter 71 fortransmitting said signals to a user. The transmitter in question may,for example, be a radio transmitter or a sonic transmitter. Naturally,the transmitter 71 can also be included in the system even if there isno learning function in the system.

FIG. 8 shows an alternative view of hardware that is comprised in thesystem 11 of the invention.

The hardware shown in FIG. 8 comprises the processing unit 13, themicrophone or acoustic transducer 12, and as an alternative to thefilter 14 there is shown as so called audio reconstruction unit ARPU 14.The implant 17 is also shown. The processing unit 13 runs softwarestored in the memory 15, which is a bidirectional memory which can alsostore other parameters and which can also log parameters. As indicatedby means of the reference number 16, the processing unit also serves therole of the command generator illustrated previously, with the aid ofthe memory 15.

The processing unit can be a microcontroller, a digital signal processoror some other processing device with the ability to run voicerecognition software. The processing unit could also be an applicationspecific integrated circuit with hardware support for the voicerecognition. The processing unit could also be a combination of thetypes mentioned above.

As mentioned previously, in some of its embodiments, the inventivesystem 11 has the ability not only to correct received audio signals forthe transfer function of the body and possibly also of a watertightcasing, but the system 11 also has the ability to cancel noise caused bythe body. This can be the task of the Audio Reconstruction ProcessingUnit, the ARPU. The ARPU can perform this function in a number of ways,for example by means of low-pass, band-pass, and high-pass filters suchas Butterworth, Bessel etc. or more advanced filters such as Sub-bandAdaptive Filters, SAF. Sub-band Adaptive filters, SAF, will be describedbriefly below, with reference to FIG. 9. Sub-band filters first dividethe signal into different frequency bands, and then each sub-band isfiltered independently. The advantage of this is that the computationalcost is lower, and the convergence of the adaptive part of the filter isfaster.

FIG. 9 shows a generic sub-band filter, and if the sub-band processingblocks are adaptive, the system is a sub-band adaptive filter. As can beseen in the figure, the filter has two inputs, the primary signal and areference signal. The primary signal should be the noisy signalcontaining the speech signal, and the reference signal a signal withmostly coherent noise. A common method of adapting the sub-bandprocessing blocks is the Least Mean Squares method, LMS.

In some applications, it is difficult to place two microphones in such away that one of them picks up the voice signal, and the other one onlypicks up coherent noise. To be able to get a good noise cancellationanyway, a Voice Activity Detector, a VAD, can be used. A VAD detectswhen there is a voice signal present on the primary input, and when thisis the case, the adaptive filter halts its adaptation, and the inputsignal is connected to the primary input. In this manner, one microphonecan alter between being the reference and the primary signal.

In FIG. 10, a processing block of a sub-band adaptive filter is shown.The estimated noise, w_(k)(n), is subtracted from the input signal. Thenoise estimation is based on Least Mean Squares algorithm, and isupdated when the VAD signal is inactive.

Regarding the acoustic transducer or microphone 12, one way of improvingthe overall system performance is to use an array of microphones ratherthan just one microphone. The filtering techniques can then be based ondifferences between the received signals; if the transducers areuni-directional, the ARPU and/or the processing unit 13 can determinewhich signals that are noise and which signals that are the actual voicecommands of a speaker, if one of the microphones is directed towards thevoice commands or signals, and one microphone is directed in theopposite direction.

FIG. 11 shows a block diagram of another alternative design of thesystem 11 of the invention. As shown here, there is comprised an ADC, ananalogue to digital converter in the system, placed immediatelyfollowing the command input device 12, here shown as a microphone,“mic”. The processing device, the filter and the command generator arehere shown as being comprised in one and the same block, such as aprocessor, for example a micro-processor which interfaces with anI/O-interface in the implant 17 and with a memory. The processing devicecan be either a so called GP MCU, a general purpose micro controllerunit or a so called GP DSP, a general purpose digital signal processor.

Regarding the software which is used in a system 11 of the presentinvention, it is suitably divided into two parts, the voice recognitionand learning algorithms, and the implant control algorithms. The implantcontrol part of the software is suitably be tailored for each implantapplication for which it is intended.

Turning now to the voice recognition algorithms, there are a number ofdifferent ways to implement such algorithms. A received audio command isin one embodiment converted to digital form, as shown above, by means ofan ADC, and is then subjected to so called “frame blocking”, windowingand FFT, Fast Fourier Transform, where the FFT is used in order toobtain a representation of the signal in the frequency domain.

As an example, the signal which is obtained by means of the FFT can alsobe exposed to so called feature extraction, following which the signalis subjected to pattern matching, to match a received command withstored commands, in order to see if the received command exhibits asufficient likeness to one of a set of stored commands. The term“sufficient likeness” is here used to signify that a threshold issuitably used for the comparison.

As examples of pattern matching algorithms, the following can bementioned:

-   -   Dynamic Time Warping    -   Hidden Markov Models    -   Artificial Neural Networks    -   Vector Quantization

As has been mentioned previously, the speech recognition can be eitherspeaker dependent or speaker independent. If the recognition is speakerdependent or speaker independent depends mainly on if the recognitionengine is trained with different speakers or just one. It is howeveralso possible to change the features used, and to optimize the patternmatching method for either speaker dependent or speaker independentrecognition.

Before speaker dependent recognition can be done, the system has tolearn the characteristics of the speaker's voice. This is done during atraining phase where the speaker utters each of the different commands afew times, so that the recognition software can adapt the patternmatching variables according to that specific speaker.

A state diagram for different states which can be assumed by the voicerecognition part of the software of the present invention is shown inFIG. 12, and described briefly below:

The implant is in Sleep mode to preserve energy when it doesn't performany other tasks. It leaves the sleep state when an “awake event” isreceived and goes to the wait state. From the wait state, the implanteither performs controlling of the implant and returns to the waitstate, or it can have received an “audio wake-up event”, if speech hasbeen detected and then processed by the ARPU, and is determined to be avalid command from a validated speaker, the command is executed, and theprogram returns to the wait state. From the wait state, the implantreturns to sleep mode if no more tasks is to be done, and no more voicecommands are given.

As mentioned, in one embodiment the inventive system makes use of a socalled ARPU, an Audio Reconstruction Processing Unit. A block diagram ofa possible such ARPU 32 is shown in FIG. 13. The ARPU is shown ascomprising a passive filter 31 which receives its input from an audioinput device, and a generic DSP 32, about which the following can besaid:

The DSP 32 comprises an analogue input, to which the signals from thefilter 31 are connected. There the analogue signal is amplified, andmore post amplification filtering can be done before the signal isquantized by a sigma-delta analogue-to-digital converter. A WOLA filterbank can then perform a number of different operations, includingdigital filtering, either by traditional IIR/FIR filters or by moreadvanced filters, such as sub-band adaptive filters.

The filtering, analysis and synthesis can be done on sub-bands todecrease computational complexity and to increase convergence rates onadaptive filters. Since the filter-bank is highly over-sampled, thealias effects of the sub-bands are small. A windowing function can beapplied to minimize signal discontinuities in the beginning and end ofthe sample. Other examples of operations that can be made in thefilter-bank includes time folding and equalization.

The system of the invention needs to be powered, which can be done in anumber of ways, some of which will be described in the following.

The system of the invention will also be referred to below as “theapparatus”. FIG. 14 illustrates one embodiment of a system 300 forsupplying the first system of the present invention with energy, withthe inventive system here being given the reference number 10. Thesystem 10 is, by way of example, in FIG. 14 shown as being placed in theabdomen of a patient; the implant which is to be controlled via thesystem 10 is not shown in FIG. 14.

In one embodiment, an implantable energy-transforming device 302 isadapted to supply energy consuming components of the apparatus 10 withenergy via a power supply line 303. An external energy-transmissiondevice 304 for non-invasively energizing the apparatus 10 transmitsenergy to the implantable energy-transforming device 302 by at least onewireless energy signal. The implanted energy-transforming device 302transforms energy from the wireless energy signal into electrical energywhich is supplied via the power supply line 303.

The wireless energy signal may include a wave signal selected from thefollowing: a sound wave signal, an ultrasound wave signal, anelectromagnetic wave signal, an infrared light signal, a visible lightsignal, an ultra violet light signal, a laser light signal, a micro wavesignal, a radio wave signal, an x-ray radiation signal and a gammaradiation signal. Alternatively, the wireless energy signal may includean electric or magnetic field, or a combined electric and magneticfield.

The wireless energy-transmission device 304 may transmit a carriersignal for carrying the wireless energy signal. Such a carrier signalmay include digital, analogue or a combination of digital and analoguesignals. In this case, the wireless energy signal includes an analogueor a digital signal, or a combination of an analogue and digital signal.

Generally speaking, the energy-transforming device 302 is provided fortransforming wireless energy of a first form transmitted by theenergy-transmission device 304 into energy of a second form, whichtypically is different from the energy of the first form. The implantedapparatus 10 is operable in response to the energy of the second form.The energy-transforming device 302 may directly power the apparatus withthe second form energy, as the energy-transforming device 302 transformsthe first form energy transmitted by the energy-transmission device 304into the second form energy. The system may further include animplantable accumulator, wherein the second form energy is used at leastpartly to charge the accumulator.

Alternatively, the wireless energy transmitted by theenergy-transmission device 304 may be used to directly power theapparatus 10, as the wireless energy is being transmitted by theenergy-transmission device 304. Where the system comprises an operationdevice for operating the apparatus, as will be described below, thewireless energy transmitted by the energy-transmission device 304 may beused to directly power the operation device to create kinetic energy forthe operation of the apparatus.

The wireless energy of the first form may comprise sound waves and theenergy-transforming device 302 may include a piezo-electric element fortransforming the sound waves into electric energy. The energy of thesecond form may comprise electric energy in the form of a direct currentor pulsating direct current, or a combination of a direct current andpulsating direct current, or an alternating current or a combination ofa direct and alternating current. Normally, the apparatus compriseselectric components that are energized with electrical energy. Otherimplantable electric components of the system may be at least onevoltage level guard or at least one constant current guard connectedwith the electric components of the apparatus.

Optionally, one of the energy of the first form and the energy of thesecond form may comprise magnetic energy, kinetic energy, sound energy,chemical energy, radiant energy, electromagnetic energy, photo energy,nuclear energy or thermal energy. Preferably, one of the energy of thefirst form and the energy of the second form is non-magnetic,non-kinetic, non-chemical, non-sonic, non-nuclear or non-thermal.

The energy-transmission device may be controlled from outside thepatient's body to release electromagnetic wireless energy, and thereleased electromagnetic wireless energy is used for operating theapparatus.

Alternatively, the energy-transmission device is controlled from outsidethe patient's body to release non-magnetic wireless energy, and thereleased non-magnetic wireless energy is used for operating theapparatus.

The external energy-transmission device 304 can also, in one embodiment,include a wireless remote control having an external signal transmitterfor transmitting a wireless control signal for non-invasivelycontrolling the apparatus. The control signal is received by animplanted signal receiver which may be incorporated in the implantedenergy-transforming device 302 or be separate there from.

The wireless control signal may include a frequency, amplitude, or phasemodulated signal or a combination thereof. Alternatively, the wirelesscontrol signal includes an analogue or a digital signal, or acombination of an analogue and digital signal. Alternatively, thewireless control signal comprises an electric or magnetic field, or acombined electric and magnetic field.

The wireless remote control may transmit a carrier signal for carryingthe wireless control signal. Such a carrier signal may include digital,analogue or a combination of digital and analogue signals. Where thecontrol signal includes an analogue or a digital signal, or acombination of an analogue and digital signal, the wireless remotecontrol preferably transmits an electromagnetic carrier wave signal forcarrying the digital or analogue control signals.

FIG. 15 illustrates the system of FIG. 4 in the form of a moregeneralized block diagram showing the system 10, the energy-transformingdevice 302 powering the apparatus 10 via power supply line 303, and theexternal energy-transmission device 304, The patient's skin 305,generally shown by a vertical line, separates the interior of thepatient to the right of the line from the exterior to the left of theline.

FIG. 16 shows an embodiment of the invention identical to that of FIG.15, except that a reversing device in the form of an electric switch 306operable for example by polarized energy also is implanted in thepatient for reversing the apparatus or system 10. When the switch isoperated by polarized energy, the wireless remote control of theexternal energy-transmission device 304 transmits a wireless signal thatcarries polarized energy and the implanted energy-transforming device302 transforms the wireless polarized energy into a polarized currentfor operating the electric switch 306. When the polarity of the currentis shifted by the implanted energy-transforming device 302 the electricswitch 306 reverses the function performed by the apparatus 10.

In all of the embodiments described herein, the energy-transformingdevice 302 may include a rechargeable accumulator like a battery or acapacitor to be charged by the wireless energy and supplies energy forany energy consuming part of the system.

FIG. 17 shows an embodiment of the invention comprising the externalenergy-transmission device 304, the apparatus 10, the implantedenergy-transforming device 302, an implanted internal control unit 315controlled by the wireless remote control of the externalenergy-transmission device 304, an implanted accumulator 316 and animplanted capacitor 317.

The internal control unit 315 arranges storage of electric energyreceived from the implanted energy-transforming device 302 in theaccumulator 316, which supplies energy to the apparatus 10. In responseto a control signal from the wireless remote control of the externalenergy-transmission device 304, the internal control unit 315 eitherreleases electric energy from the accumulator 316 and transfers thereleased energy via power lines 318 and 319, or directly transferselectric energy from the implanted energy-transforming device 302 via apower line 320, the capacitor 317, which stabilizes the electriccurrent, a power line 321 and the power line 319, for the operation ofthe apparatus 10.

The internal control unit is preferably programmable from outside thepatient's body. In a preferred embodiment, the internal control unit isprogrammed to regulate the apparatus 10 according to a pre-programmedtime-schedule or to input from any sensor sensing any possible physicalparameter of the patient or any functional parameter of the system.

In accordance with an alternative, the capacitor 317 in the embodimentof FIG. 17 may be omitted. In accordance with another alternative, theaccumulator 316 in this embodiment may be omitted.

FIG. 18 shows an embodiment of the invention identical to that of FIG.15, except that a battery 322 for supplying energy for the operation ofthe apparatus 10 and an electric switch 323 for switching the operationof the apparatus 10 are also implanted in the patient. The electricswitch 323 may be controlled by the remote control and may also beoperated by the energy supplied by the implanted energy-transformingdevice 302 to switch from an off mode, in which the battery 322 is notin use, to an on mode, in which the battery 322 supplies energy for theoperation of the apparatus 10.

FIG. 19 shows an embodiment of the invention identical to that of FIG.18, except that an internal control unit 315 controllable by a wirelessremote control of the external energy-transmission device 304 also isimplanted in the patient. In this case, the electric switch 323 isoperated by the energy supplied by the implanted energy-transformingdevice 302 to switch from an off mode, in which the wireless remotecontrol is prevented from controlling the internal control unit 315 andthe battery is not in use, to a standby mode, in which the remotecontrol is permitted to control the internal control unit 315 to releaseelectric energy from the battery 322 for the operation of the apparatus10.

FIG. 20 shows an embodiment of the invention identical to that of FIG.19, except that an accumulator 316 is substituted for the battery 322and the implanted components are interconnected differently. In thiscase, the accumulator 316 stores energy from the implantedenergy-transforming device 302. In response to a control signal from thewireless remote control of the external energy-transmission device 304,the internal control unit 315 controls the electric switch 323 to switchfrom an off mode, in which the accumulator 316 is not in use, to an onmode, in which the accumulator 316 supplies energy for the operation ofthe apparatus 10. The accumulator may be combined with or replaced by acapacitor.

FIG. 21 shows an embodiment of the invention identical to that of FIG.20, except that a battery 322 also is implanted in the patient and theimplanted components are interconnected differently. In response to acontrol signal from a wireless remote control of the externalenergy-transmission device 304, the internal control unit 315 controlsthe accumulator 316 to deliver energy for operating the electric switch323 to switch from an off mode, in which the battery 322 is not in use,to an on mode, in which the battery 322 supplies electric energy for theoperation of the apparatus 10.

Alternatively, the electric switch 323 may be operated by energysupplied by the accumulator 316 to switch from an off mode, in which thewireless remote control is prevented from controlling the battery 322 tosupply electric energy and is not in use, to a standby mode, in whichthe wireless remote control is permitted to control the battery 322 tosupply electric energy for the operation of the apparatus 10.

It should be understood that the switch 323 and all other switches inthis application should be interpreted in its broadest embodiment. Thismeans a transistor, MCU, MCPU, ASIC, FPGA or a DA converter or any otherelectronic component or circuit that may switch the power on and off.Preferably the switch is controlled from outside the body, oralternatively by an implanted internal control unit.

FIG. 22 shows an embodiment of the invention identical to that of FIG.19 except that the implanted components are interconnected differently.Thus, in this case, the internal control unit 315 is powered by thebattery 322 when the accumulator 316, suitably a capacitor, activatesthe electric switch 323 to switch to an “on” mode. When the electricswitch 323 is in its “on” mode, the internal control unit 315 ispermitted to control the battery 322 to supply, or not supply, energyfor the operation of the apparatus 10.

FIG. 23 schematically shows conceivable combinations of implantedcomponents of the apparatus for achieving various communication options.Basically, there is the apparatus 10, the internal control unit 315, anoptional component 309, and the external energy-transmission device 304including the external wireless remote control. As already describedabove, a wireless remote control transmits a control signal which isreceived by the internal control unit 315, which in turn controls thevarious implanted components of the apparatus.

The internal control unit 315, or alternatively the external wirelessremote control of the external energy-transmission device 304, maycontrol the apparatus 10 in response to signals from the sensor 325. Atransceiver may be combined with the sensor 325 for sending informationon the sensed physical parameter to the external wireless remotecontrol. The wireless remote control may comprise a signal transmitteror transceiver and the internal control unit 315 may comprise a signalreceiver or transceiver.

Alternatively, the wireless remote control may comprise a signalreceiver or transceiver and the internal control unit 315 may comprise asignal transmitter or transceiver. The above transceivers, transmittersand receivers may be used for sending information or data related to theapparatus 10 from inside the patient's body to the outside thereof.

Where the battery 322 for powering the apparatus 10 is implanted,information related to the charging of the battery 322 may be fed back.To be more precise, when charging a battery or accumulator with energy,feedback information related to said charging process is sent and theenergy supply is changed accordingly. This information is suitably sentvia the communication between the first and second parts of theinventive system.

An internal energy receiver can be adapted to directly or indirectlysupply received energy to the energy consuming components of theapparatus 10 via a switch 326. An energy balance is determined betweenthe energy received by the internal energy receiver 302 and the energyused for the apparatus 10, and the transmission of wireless energy isthen controlled based on the determined energy balance. The energybalance thus provides an accurate indication of the correct amount ofenergy needed, which is sufficient to operate the apparatus 10 properly,but without causing undue temperature rise.

In FIGS. 15-22, the patient's skin is indicated by a vertical line 305.Here, the energy receiver comprises an energy-transforming device 302located inside the patient, preferably just beneath the patient's skin305. Generally speaking, the implanted energy-transforming device 302may be placed in the abdomen, thorax, muscle fascia (e.g. in theabdominal wall), subcutaneously, or at any other suitable location. Theimplanted energy-transforming device 302 is adapted to receive wirelessenergy E transmitted from the external energy-source 304 a provided inan external energy-transmission device 304 located outside the patient'sskin 305 in the vicinity of the implanted energy-transforming device302.

As is well known in the art, the wireless energy E may generally betransferred by means of any suitable Transcutaneous Energy Transfer(TET) device, such as a device including a primary coil arranged in theexternal energy source 304 a and an adjacent secondary coil arranged inthe implanted energy-transforming device 302. When an electric currentis fed through the primary coil, energy in the form of a voltage isinduced in the secondary coil which can be used to power the implantedenergy consuming components of the apparatus, e.g. after storing theincoming energy in an implanted energy source, such as a rechargeablebattery or a capacitor.

However, the present invention is generally not limited to anyparticular energy transfer technique, TET devices or energy sources, andany kind of wireless energy may be used. The amount of energy receivedby the implanted energy receiver may be compared with the energy used bythe implanted components of the apparatus. The term “energy used” isthen understood to include also energy stored by implanted components ofthe apparatus.

A control device includes an external control unit that controls theexternal energy source 304 a based on the determined energy balance toregulate the amount of transferred energy. In order to transfer thecorrect amount of energy, the energy balance and the required amount ofenergy is determined by means of a determination device including animplanted internal control unit 315 connected between the switch 326 andthe apparatus 10. The internal control unit 315 may thus be arranged toreceive various measurements obtained by suitable sensors or the like,not shown, measuring certain characteristics of the apparatus 10,somehow reflecting the required amount of energy needed for properoperation of the apparatus 10.

Moreover, the current condition of the patient may also be detected bymeans of suitable measuring devices or sensors, in order to provideparameters reflecting the patient's condition. Hence, suchcharacteristics and/or parameters may be related to the current state ofthe apparatus 10, such as power consumption, operational mode andtemperature, as well as the patient's condition reflected by parameterssuch as; body temperature, blood pressure, heartbeats and breathing.Other kinds of physical parameters of the patient and functionalparameters of the device are described elsewhere.

Furthermore, an energy source in the form of an accumulator 316 mayoptionally be connected to the implanted energy-transforming device 302via the control unit 315 for accumulating received energy for later useby the apparatus 10. Alternatively or additionally, characteristics ofsuch an accumulator, also reflecting the required amount of energy, maybe measured as well. The accumulator may be replaced by a rechargeablebattery, and the measured characteristics may be related to the currentstate of the battery, any electrical parameter such as energyconsumption voltage, temperature, etc. In order to provide sufficientvoltage and current to the apparatus 10, and also to avoid excessiveheating, it is clearly understood that the battery should be chargedoptimally by receiving a correct amount of energy from the implantedenergy-transforming device 302, i.e. not too little or too much. Theaccumulator may also be a capacitor with corresponding characteristics.

For example, battery characteristics may be measured on a regular basisto determine the current state of the battery, which then may be storedas state information in a suitable storage means in the internal controlunit 315. Thus, whenever new measurements are made, the stored batterystate information can be updated accordingly. In this way, the state ofthe battery can be “calibrated” by transferring a correct amount ofenergy, so as to maintain the battery in an optimal condition.

Thus, the internal control unit 315 of the determination device isadapted to determine the energy balance and/or the currently requiredamount of energy, (either energy per time unit or accumulated energy)based on measurements made by the above-mentioned sensors or measuringdevices of the apparatus 10, or the patient, or an implanted energysource if used, or any combination thereof. The internal control unit315 is further connected to an internal signal transmitter 327, arrangedto transmit a control signal reflecting the determined required amountof energy, to an external signal receiver 304 c connected to theexternal control unit 304 b. The amount of energy transmitted from theexternal energy source 304 a may then be regulated in response to thereceived control signal.

Alternatively, the determination device may include the external controlunit 304 b. In this alternative, sensor measurements can be transmitteddirectly to the external control unit 304 b wherein the energy balanceand/or the currently required amount of energy can be determined by theexternal control unit 304 b, thus integrating the above-describedfunction of the internal control unit 315 in the external control unit304 b. In that case, the internal control unit 315 can be omitted andthe sensor measurements are supplied directly to the internal signaltransmitter 327 which sends the measurements over to the external signalreceiver 304 c and the external control unit 304 b.

The energy balance and the currently required amount of energy can thenbe determined by the external control unit 304 b based on those sensormeasurements.

Hence, the present solution can employ the feedback of informationindicating the required energy, which is more efficient than many othersolutions since it is based on the actual use of energy that is comparedto the received energy, e.g. with respect to the amount of energy, theenergy difference, or the energy receiving rate as compared to theenergy rate used by implanted energy consuming components of theapparatus. The apparatus may use the received energy either forconsuming or for storing the energy in an implanted energy source or thelike. The different parameters discussed above would thus be used ifrelevant and needed and then as a tool for determining the actual energybalance. However, such parameters may also be needed per se for anyactions taken internally to specifically operate the apparatus.

Thus, the feedback information may be transferred either by a separatecommunication system including receivers and transmitters or may beintegrated in the energy system, or by means of the communicationbetween the first and the second part of the system. In accordance withone embodiment of the present invention, such an integrated informationfeedback and energy system comprises an implantable internal energyreceiver for receiving wireless energy, the energy receiver having aninternal first coil and a first electronic circuit connected to thefirst coil, and an external energy transmitter for transmitting wirelessenergy, the energy transmitter having an external second coil and asecond electronic circuit connected to the second coil.

The external second coil of the energy transmitter transmits wirelessenergy which is received by the first coil of the energy receiver. Thisembodiment of the inventive system further comprises a power switch forswitching the connection of the internal first coil to the firstelectronic circuit on and off, such that feedback information related tothe charging of the first coil is received by the external energytransmitter in the form of an impedance variation in the load of theexternal second coil, when the power switch switches the connection ofthe internal first coil to the first electronic circuit on and off. Inimplementing this embodiment of the system, the switch is eitherseparate and controlled by the internal control unit 315, or integratedin the internal control unit 315. It should be understood that theswitch 326 should be interpreted in its broadest embodiment. This meansa transistor, MCU, MCPU, ASIC FPGA or a DA converter or any otherelectronic component or circuit that may switch the power on and off.

To conclude, this embodiment of the energy supply arrangement mayoperate basically in the following manner: The energy balance is firstdetermined by the internal control unit 315 of the determination device.A control signal reflecting the required amount of energy is alsocreated by the internal control unit 315, and the control signal istransmitted from the internal signal transmitter 327 to the externalsignal receiver 304 c. Alternatively, the energy balance can bedetermined by the external control unit 304 b instead depending on theimplementation, as mentioned above. In that case, the control signal maycarry measurement results from various sensors.

The amount of energy emitted from the external energy source 304 a canthen be regulated by the external control unit 304 b, based on thedetermined energy balance, e.g. in response to the received controlsignal. This process may be repeated intermittently at certain intervalsduring ongoing energy transfer, or may be executed on a more or lesscontinuous basis during the energy transfer.

The amount of transferred energy can generally be regulated by adjustingvarious transmission parameters in the external energy source 304 a,such as voltage, current, amplitude, wave frequency and pulsecharacteristics.

This system may also be used to obtain information about the couplingfactors between the coils in a TET system even to calibrate the systemboth to find an optimal place for the external coil in relation to theinternal coil and to optimize energy transfer. Simply comparing in thiscase the amount of energy transferred with the amount of energyreceived. For example if the external coil is moved the coupling factormay vary and correctly displayed movements could cause the external coilto find the optimal place for energy transfer. Preferably, the externalcoil is adapted to calibrate the amount of transferred energy to achievethe feedback information in the determination device, before thecoupling factor is maximized.

This coupling factor information may also be used as a feedback duringenergy transfer. In such a case, the energy system of the presentinvention comprises an implantable internal energy receiver forreceiving wireless energy, the energy receiver having an internal firstcoil and a first electronic circuit connected to the first coil, and anexternal energy transmitter for transmitting wireless energy, the energytransmitter having an external second coil and a second electroniccircuit connected to the second coil.

The external second coil of the energy transmitter transmits wirelessenergy which is received by the first coil of the energy receiver. Thissystem further comprises a feedback device for communicating out theamount of energy received in the first coil as a feedback information,and wherein the second electronic circuit includes a determinationdevice for receiving the feedback information and for comparing theamount of transferred energy by the second coil with the feedbackinformation related to the amount of energy received in the first coilto obtain the coupling factor between the first and second coils. Theenergy transmitter may regulate the transmitted energy in response tothe obtained coupling factor.

With reference to FIG. 24, although wireless transfer of energy foroperating the apparatus has been described above to enable non-invasiveoperation, it will be appreciated that the apparatus can be operatedwith wire bound energy as well. Such an example is shown in FIG. 25,wherein an external switch 326 is interconnected between the externalenergy source 304 a and an operation device, such as an electric motor307 operating the apparatus 10. An external control unit 304 b controlsthe operation of the external switch 326 to effect proper operation ofthe apparatus 10.

FIG. 25 illustrates different embodiments for how received energy can besupplied to and used by the apparatus 10. Similar to the example of FIG.24, an internal energy receiver 302 receives wireless energy E from anexternal energy source 304 a which is controlled by a transmissioncontrol unit 304 b. The internal energy receiver 302 may comprise aconstant voltage circuit, indicated as a dashed box “constant V” in thefigure, for supplying energy at constant voltage to the apparatus 10.The internal energy receiver 302 may further comprise a constant currentcircuit, indicated as a dashed box “constant C” in the figure, forsupplying energy at constant current to the apparatus 10.

The apparatus 10 comprises an energy consuming part 10 a, that requiresenergy for its electrical operation. The apparatus 10 may furthercomprise an energy storage device 10 b for storing energy supplied fromthe internal energy receiver 302. Thus, the supplied energy may bedirectly consumed by the energy consuming part 10 a, or stored by theenergy storage device 10 b, or the supplied energy may be partlyconsumed and partly stored. The apparatus 10 may further comprise anenergy stabilizing unit 10 c for stabilizing the energy supplied fromthe internal energy receiver 302. Thus, the energy may be supplied in afluctuating manner such that it may be necessary to stabilize the energybefore consumed or stored.

The energy supplied from the internal energy receiver 302 may further beaccumulated and/or stabilized by a separate energy stabilizing unit 328located outside the apparatus 10, before being consumed and/or stored bythe apparatus 10. Alternatively, the energy stabilizing unit 328 may beintegrated in the internal energy receiver 302. In either case, theenergy stabilizing unit 328 may comprise a constant voltage circuitand/or a constant current circuit.

It should be noted that FIG. 24 and FIG. 25 illustrate some possible butnon-limiting implementation options regarding how the various shownfunctional components and elements can be arranged and connected to eachother. However, the skilled person will readily appreciate that manyvariations and modifications can be made within the scope of the presentinvention.

FIG. 26 schematically shows an energy balance measuring circuit of oneof the proposed designs of the system for controlling transmission ofwireless energy, or energy balance control system. The circuit has anoutput signal centered on 2.5V and proportionally related to the energyimbalance. The derivative of this signal shows if the value goes up anddown and how fast such a change takes place. If the amount of receivedenergy is lower than the energy used by implanted components of theapparatus, more energy is transferred and thus charged into the energysource.

The output signal from the circuit is typically feed to an ND converterand converted into a digital format. The digital information can then besent to the external energy-transmission device allowing it to adjustthe level of the transmitted energy. Another possibility is to have acompletely analog system that uses comparators comparing the energybalance level with certain maximum and minimum thresholds sendinginformation to external energy-transmission device if the balance driftsout of the max/min window.

The schematic FIG. 26 shows a circuit implementation for a system thattransfers energy to the implanted energy components of the apparatus ofthe present invention from outside of the patient's body using inductiveenergy transfer. An inductive energy transfer system typically uses anexternal transmitting coil and an internal receiving coil.

The implementation of the general concept of energy balance and the waythe information is transmitted to the external energy transmitter can ofcourse be implemented in numerous different ways. The schematic FIG. 26and the above described method of evaluating and transmitting theinformation should only be regarded as examples of how to implement thecontrol system.

Circuit Details

In FIG. 26 the symbols Y1, Y2, Y3 and so on symbolize test points withinthe circuit. The components in the diagram and their respective valuesare values that work in this particular implementation which of courseis only one of an infinite number of possible design solutions.

Energy to power the circuit is received by the energy receiving coil L1.Energy to implanted components is transmitted in this particular case ata frequency of 25 kHz. The energy balance output signal is present attest point Y1.

Those skilled in the art will realize that the above various embodimentsof the system could be combined in many different ways. For example, anelectric switch could be incorporated in any of the embodiments of FIGS.14-25. Please observe that the switch simply could mean any electroniccircuit or component.

The embodiments described in connection with FIGS. 25 and 26 identify amethod and a system for controlling transmission of wireless energy toimplanted energy consuming components of an electrically operableapparatus. Such a method and system will be defined in general terms inthe following.

A method is thus provided for controlling transmission of wirelessenergy supplied to implanted energy consuming components of an apparatusas described above. The wireless energy E is transmitted from anexternal energy source located outside the patient and is received by aninternal energy receiver located inside the patient, the internal energyreceiver being connected to the implanted energy consuming components ofthe apparatus for directly or indirectly supplying received energythereto. An energy balance is determined between the energy received bythe internal energy receiver and the energy used for the apparatus. Thetransmission of wireless energy E from the external energy source isthen controlled based on the determined energy balance.

The wireless energy may be transmitted inductively from a primary coilin the external energy source to a secondary coil in the internal energyreceiver. A change in the energy balance may be detected to control thetransmission of wireless energy based on the detected energy balancechange. A difference may also be detected between energy received by theinternal energy receiver and energy used for the medical device, tocontrol the transmission of wireless energy based on the detected energydifference.

When controlling the energy transmission, the amount of transmittedwireless energy may be decreased if the detected energy balance changeimplies that the energy balance is increasing, or vice versa. Thedecrease/increase of energy transmission may further correspond to adetected change rate.

The amount of transmitted wireless energy may further be decreased ifthe detected energy difference implies that the received energy isgreater than the used energy, or vice versa. The decrease/increase ofenergy transmission may then correspond to the magnitude of the detectedenergy difference.

As mentioned above, the energy used for the medical device may beconsumed to operate the medical device, and/or stored in at least oneenergy storage device of the medical device.

When electrical and/or physical parameters of the medical device and/orphysical parameters of the patient are determined, the energy may betransmitted for consumption and storage according to a transmission rateper time unit which is determined based on said parameters. The totalamount of transmitted energy may also be determined based on saidparameters.

When a difference is detected between the total amount of energyreceived by the internal energy receiver and the total amount ofconsumed and/or stored energy, and the detected difference is related tothe integral over time of at least one measured electrical parameterrelated to said energy balance, the integral may be determined for amonitored voltage and/or current related to the energy balance.

When the derivative is determined over time of a measured electricalparameter related to the amount of consumed and/or stored energy, thederivative may be determined for a monitored voltage and/or currentrelated to the energy balance.

The transmission of wireless energy from the external energy source maybe controlled by applying to the external energy source electricalpulses from a first electric circuit to transmit the wireless energy,the electrical pulses having leading and trailing edges, varying thelengths of first time intervals between successive leading and trailingedges of the electrical pulses and/or the lengths of second timeintervals between successive trailing and leading edges of theelectrical pulses, and transmitting wireless energy, the transmittedenergy generated from the electrical pulses having a varied power, thevarying of the power depending on the lengths of the first and/or secondtime intervals.

In that case, the frequency of the electrical pulses may besubstantially constant when varying the first and/or second timeintervals. When applying electrical pulses, the electrical pulses mayremain unchanged, except for varying the first and/or second timeintervals. The amplitude of the electrical pulses may be substantiallyconstant when varying the first and/or second time intervals. Further,the electrical pulses may be varied by only varying the lengths of firsttime intervals between successive leading and trailing edges of theelectrical pulses.

A train of two or more electrical pulses may be supplied in a row,wherein when applying the train of pulses, the train having a firstelectrical pulse at the start of the pulse train and having a secondelectrical pulse at the end of the pulse train, two or more pulse trainsmay be supplied in a row, wherein the lengths of the second timeintervals between successive trailing edge of the second electricalpulse in a first pulse train and leading edge of the first electricalpulse of a second pulse train are varied.

When applying the electrical pulses, the electrical pulses may have asubstantially constant current and a substantially constant voltage. Theelectrical pulses may also have a substantially constant current and asubstantially constant voltage. Further, the electrical pulses may alsohave a substantially constant frequency. The electrical pulses within apulse train may likewise have a substantially constant frequency.

The circuit formed by the first electric circuit and the external energysource may have a first characteristic time period or first timeconstant, and when effectively varying the transmitted energy, suchfrequency time period may be in the range of the first characteristictime period or time constant or shorter.

A system comprising an apparatus as described above is thus alsoprovided for controlling transmission of wireless energy supplied toimplanted energy consuming components of the apparatus. In its broadestsense, the system comprises a control device for controlling thetransmission of wireless energy from an energy-transmission device, andan implantable internal energy receiver for receiving the transmittedwireless energy, the internal energy receiver being connected toimplantable energy consuming components of the apparatus for directly orindirectly supplying received energy thereto.

The system further comprises a determination device adapted to determinean energy balance between the energy received by the internal energyreceiver and the energy used for the implantable energy consumingcomponents of the apparatus, wherein the control device controls thetransmission of wireless energy from the external energy-transmissiondevice, based on the energy balance determined by the determinationdevice.

Further, the system may comprise any of the following:

-   -   A primary coil in the external energy source adapted to transmit        the wireless energy inductively to a secondary coil in the        internal energy receiver.    -   The determination device is adapted to detect a change in the        energy balance, and the control device controls the transmission        of wireless energy based on the detected energy balance change    -   The determination device is adapted to detect a difference        between energy received by the internal energy receiver and        energy used for the implantable energy consuming components of        the apparatus, and the control device controls the transmission        of wireless energy based on the detected energy difference.    -   The control device controls the external energy-transmission        device to decrease the amount of transmitted wireless energy if        the detected energy balance change implies that the energy        balance is increasing, or vice versa, wherein the        decrease/increase of energy transmission corresponds to a        detected change rate.    -   The control device controls the external energy-transmission        device to decrease the amount of transmitted wireless energy if        the detected energy difference implies that the received energy        is greater than the used energy, or vice versa, wherein the        decrease/increase of energy transmission corresponds to the        magnitude of said detected energy difference.    -   The energy used for the apparatus is consumed to operate the        apparatus, and/or stored in at least one energy storage device        of the apparatus.    -   Where electrical and/or physical parameters of the apparatus        and/or physical parameters of the patient are determined, the        energy-transmission device transmits the energy for consumption        and storage according to a transmission rate per time unit which        is determined by the determination device based on said        parameters. The determination device also determines the total        amount of transmitted energy based on said parameters.    -   When a difference is detected between the total amount of energy        received by the internal energy receiver and the total amount of        consumed and/or stored energy, and the detected difference is        related to the integral over time of at least one measured        electrical parameter related to the energy balance, the        determination device determines the integral for a monitored        voltage and/or current related to the energy balance.    -   When the derivative is determined over time of a measured        electrical parameter related to the amount of consumed and/or        stored energy, the determination device determines the        derivative for a monitored voltage and/or current related to the        energy balance.    -   The energy-transmission device comprises a coil placed        externally to the human body, and an electric circuit is        provided to power the external coil with electrical pulses to        transmit the wireless energy. The electrical pulses have leading        and trailing edges, and the electric circuit is adapted to vary        first time intervals between successive leading and trailing        edges and/or second time intervals between successive trailing        and leading edges of the electrical pulses to vary the power of        the transmitted wireless energy. As a result, the energy        receiver receiving the transmitted wireless energy has a varied        power.    -   The electric circuit is adapted to deliver the electrical pulses        to remain unchanged except varying the first and/or second time        intervals.    -   The electric circuit has a time constant and is adapted to vary        the first and second time intervals only in the range of the        first time constant, so that when the lengths of the first        and/or second time intervals are varied, the transmitted power        over the coil is varied.    -   The electric circuit is adapted to deliver the electrical pulses        to be varied by only varying the lengths of first time intervals        between successive leading and trailing edges of the electrical        pulses.    -   The electric circuit is adapted to supplying a train of two or        more electrical pulses in a row, said train having a first        electrical pulse at the start of the pulse train and having a        second electrical pulse at the end of the pulse train, and    -   the lengths of the second time intervals between successive        trailing edge of the second electrical pulse in a first pulse        train and leading edge of the first electrical pulse of a second        pulse train are varied by the first electronic circuit.    -   The electric circuit is adapted to provide the electrical pulses        as pulses having a substantially constant height and/or        amplitude and/or intensity and/or voltage and/or current and/or        frequency.    -   The electric circuit has a time constant, and is adapted to vary        the first and second time intervals only in the range of the        first time constant, so that when the lengths of the first        and/or second time intervals are varied, the transmitted power        over the first coil are varied.    -   The electric circuit is adapted to provide the electrical pulses        varying the lengths of the first and/or the second time        intervals only within a range that includes the first time        constant or that is located relatively close to the first time        constant, compared to the magnitude of the first time constant.

While specific embodiments of the invention have been illustrated anddescribed herein, it should be realized that numerous other embodimentsmay be envisaged and that numerous additional advantages, modificationsand changes will readily occur to those skilled in the art withoutdeparting from the spirit and scope of the invention. Therefore, theinvention in its broader aspects is not limited to the specific details,representative devices and illustrated examples shown and describedherein. Accordingly, various modifications may be made without departingfrom the spirit or scope of the general inventive concept as defined bythe appended claims and their equivalents, and numerous otherembodiments may be envisaged without departing from the spirit and scopeof the invention.

The invention is not limited to the examples of embodiments describedabove and shown in the drawings, but may be freely varied within thescope of the appended claims.

1-51. (canceled)
 52. A system for communicating with a medical implantin a body of a user, the system comprising: an implantable commandgenerator configured to receive a voice command from the user; and amemory configured to store previously received voice commands; whereinthe implantable command generator is configured to: reduce noise,generated by the body, from the received voice command to generate anoise-reduced voice command, compare the noise-reduce voice command withthe previously received voice commands stored in the memory, andtransmit a command signal, based on the received voice command, to themedical implant in case the noise-reduced voice command corresponds toany of the previously received voice commands stored in the memory. 53.The system according to claim 52, wherein the implantable commandgenerator is configured to reduce the noise in case said noise is abovea predetermined level.
 54. The system according to claim 52, wherein thepreviously received voice commands stored in the memory arenoise-reduced voice commands.
 55. The system according to claim 52,wherein the command generator is configured to be implanted in aproximity of the medical implant.
 56. The system according to claim 52,wherein the command generator is configured to be arranged in themedical implant.
 57. The system according to claim 52, wherein thecommand generator is configured to identify a specific noise source inthe body.
 58. The system according to claim 57, wherein the commandgenerator is configured to reduce the noise in case the specific noisesource is identified.
 59. The system according to claim 52, wherein thecommand generator is configured to reduce the noise only in response tothe voice command being detected.
 60. The system according to claim 52,wherein the command generator is configured to reduce the noisegenerated from at least one of the intestines, the respiratory systemand the heart of the user.
 61. The system according to claim 52, whereinthe command generator further comprises a training functionalityconfigured to learn which of a number of voice commands that should beinterpreted as corresponding to one of a plurality of predeterminedcommands.
 62. The system according to claim 52, wherein the memory isconfigured to store a plurality of predetermined commands to betransmitted to the medical implant via the command signal.
 63. Thesystem according to claim 62, wherein the memory is configured toreceive the predetermined commands from a remote control arrangedoutside of the body.
 64. The system according to claim 63, configured toreceive the predetermined commands wirelessly from the remote control.65. The system according to claim 52, configured to be implanted in theabdomen, thorax or pelvic region of the body.
 66. The system accordingto claim 52, further comprising an implantable switch configured tonon-invasively control the operation of the medical implant.
 67. Thesystem according to claim 52, further comprising a filter configured toreduce the noise.
 68. The system according to claim 67, wherein thefilter is configured to filter the received voice command against abackground of high-frequency losses and frequency distortion caused bythe body.
 69. The system according to claim 52, further comprising aninternal energy source for powering energy consuming components of thesystem.
 70. The system according to claim 69, further comprising animplantable energy receiver configured to be connected to the energysource and to be supplied with energy from outside the body.
 71. Thesystem according to claim 70, wherein the energy receiver is configuredto be suppled with wirelessly transmitted energy.